The Eagle Supre - Big SE Amp

[Berger]

no problem thanks for the description I think I got it from that.

Aaron

[rogb]

no problem thanks for the description I think I got it from that.

Aaron

Just refer to the schematic I posted and sub the right hand tube for your octal pinout, 6V6/6L6 is 5 and 3

[yowza]

OK it took me long enough but I finally finished my Eagle earlier tonight, it fired up the first time! I kept having things get in the way of finishing the build so I'm glad to finally see it through.

With all knobs turned down there is a bit of low hum coming through the speaker, more than I think should be there. I'll have to troubleshoot further but it sounds like it might be a lead dress or ground issue. Anyone else have issues with hum on their Eagle? I've heard SE amps can hum more than push-pull. Any suggestions to get rid of this hum?

I'm using a 12AX7 and 6L6 at the moment and so far mine is "stock" with no NFB resistor. I agree with everyone here that bypassing the tone stack gives the best tone, it surprises me how much is lost through the tone stack. I might play with the tone cap values some to add a little more low end.

Switching between the high and low power taps doesn't make a lot of difference in the sound, not sure if I'll keep that switch in place.

This thing is loud!! It was too late to really crank it up but I bet it'll really sound great.

Still on my list to try out:

Play around with tone stack caps, NFB resistor values

Master volume or VVR to tame the volume.

Add another 9 pin pre amp tube to possibly parallel V1 triodes or add cathode follower tone stack (?)

Possibly add another octal or 9 pin socket for parallel power tubes, I'll have to look at the available heater voltage a little more before I add these tubes

Line out jack- to send to effects/wet amp

To RJ, Thanks for all of your help and patience with my email questions!

I finally put the DIY Eagle cab together and it looks great and once my woodworking friend rounds the cabinet corners (and shows me how to do it myself) it will be ready to finish or cover. I hope to meet up with him really soon.

If I can't figure out this hum issue I may some post pictures but to be honest my build doesn't look much different than anyone else's.

Thanks in advance for help with the hum!

Regards,
Ed

[surfsup]

Add another 9 pin pre amp tube to possibly parallel V1 triodes or add cathode follower tone stack (?)

I did this at first with a CF, then with a MOSFET. the Mosfet works great and lets you keep the triode for something else. I currently have a Mosfet CF, and a CF just before the EL34.

Possibly add another octal or 9 pin socket for parallel power tubes, I'll have to look at the available heater voltage a little more before I add these tubes.
Line out jack- to send to effects/wet amp

I'm thinking about PP as well, but need a different OT for that. I'd also like something similar to a line out, a headphone jack.

Thanks in advance for help with the hum!

One of the earlier builders had to add another smoothing cap. If you scroll up 5-6 pages maybe, you'll probably see it. Basically it was a parallel cap to the resevoir to double up. Seemed to rectify his issue from what I recall...

[surfsup]

Here;s the relevant thread, it was xtian:

http://ampgarage.com/forum/viewtopic.ph ... 6c8eab6577

The pic is no longer there cuz I never uploaded it, but the text is all there.

I used a different grounding scheme on mine.

[yowza]

Here;s the relevant thread, it was xtian:

http://ampgarage.com/forum/viewtopic.ph ... 6c8eab6577

The pic is no longer there cuz I never uploaded it, but the text is all there.

I used a different grounding scheme on mine.

Thanks surfsup! I looked for the messages about extra filtering but I couldn't find them.

I think my hum might be from the grounding scheme but I thought I followed what RJ and others did on that. The hum is very noticeable through the speaker the instant you turn the power on, before the tubes have even warmed up and it's so loud right now the amp isn't usable as is. It's a lower pitched hum that's there even if the knobs are turned all the way down, it sounds like 60 cycle hum but I'm going to measure it later with my meter and see. The amp came on fine without blowing a fuse and other than the hum it sounds good so I don't think I'm too far off track. I need to look everything over and make sure I don't have something hooked up wrong.

I'm going to troubleshoot some more before I add extra filtering, I haven't heard anyone else complaining about the hum so it must be something I've done.

What grounding scheme did you use?

Thanks for your help!
Ed

[M Fowler]

I got hum so I need to tear the chassis out of the combo cab (quite a chore) to add another cap to the main filter. My lead dress is good so I know it is the low value main filter cap.

Mark

[RJ Guitars]

...I think my hum might be from the grounding scheme but I thought I followed what RJ and others did on that. The hum is very noticeable through the speaker the instant you turn the power on, before the tubes have even warmed up and it's so loud right now the amp isn't usable as is. It's a lower pitched hum that's there even if the knobs are turned all the way down, it sounds like 60 cycle hum but I'm going to measure it later with my meter and see. The amp came on fine without blowing a fuse and other than the hum it sounds good so I don't think I'm too far off track. I need to look everything over and make sure I don't have something hooked up wrong.

I'm going to troubleshoot some more before I add extra filtering, I haven't heard anyone else complaining about the hum so it must be something I've done.

What grounding scheme did you use?

Thanks for your help!
Ed

I don't think anybody got these to be totally hum free but I think everybody is well into the the "usable" category. I am not overly familiar with Single Ended amps so no doubt there is still some I can learn and apply, although we did have some great TAG help as we went on these projects.

Xiatan is a studio guy and I think he took his the furthest toward ultra quiet although I am not sure if it ever was completely hum silent or not. I know he worked at it really hard.

I had hum in the original design that prompted me to move the output transformer... Then I added more filtering and eventually changed that first filter cap to 47uF. I did some revamping on the grounding to try and squeak the last of the audible hum out of it but it was pretty minimal at that point and didn't really make much diff...

With your description it doesn't sound like you are trying to work out the last little bit of hum so I want to ask about a couple obvious things... forgive me if these are overly simple but it should help to get the baseline established.

Did you get the center tap grounded on the heater circuit?

Can you verify that each of the ground points on the PS filtering are good?

If you have a couple pics that would be useful to give a few more eyes a look at it.

thanks,

rj

[yowza]

I don't think anybody got these to be totally hum free but I think everybody is well into the the "usable" category. I am not overly familiar with Single Ended amps so no doubt there is still some I can learn and apply, although we did have some great TAG help as we went on these projects.

Xiatan is a studio guy and I think he took his the furthest toward ultra quiet although I am not sure if it ever was completely hum silent or not. I know he worked at it really hard.

I had hum in the original design that prompted me to move the output transformer... Then I added more filtering and eventually changed that first filter cap to 47uF. I did some revamping on the grounding to try and squeak the last of the audible hum out of it but it was pretty minimal at that point and didn't really make much diff...

With your description it doesn't sound like you are trying to work out the last little bit of hum so I want to ask about a couple obvious things... forgive me if these are overly simple but it should help to get the baseline established.

Did you get the center tap grounded on the heater circuit?

Can you verify that each of the ground points on the PS filtering are good?

If you have a couple pics that would be useful to give a few more eyes a look at it.

thanks,

rj

RJ,

I apologize, I've got to be more careful when I post in a hurry (I'm at work) how my words are going to come across and "unusable" is very harsh, not what I meant to say and I'm so sorry about that. I'm one of "those" people that is really sensitive to and bothered by hum and noise so I go the extra several miles to get rid of all of it. As it is now this amp would be fine live on stage but I want to use it in the studio so I want to get it as quiet as I can without neutering it, that's what I was getting at. I just didn't say it very well.

Since I only got the amp up and running for the first time late last night I haven't had time to troubleshoot it any further. I still think my hum is not necessarily related to the filtering or that fact that it's a SE amp. It's very likely something I've done or not done, this is only the second amp I've built so I'm still learning. Even though I've played guitar for years this is the first SE amp I've ever owned and there may be a certain amount of hum that comes with SE territory and at some point I'll have to get over it.

Per our earlier email conversations I connected the heater center tap to the power tube cathode like your earlier pictures and layout diagram. After you told me about doing that I came across the info at Aiken's and Merlin's sites so I saw where you were coming from, great learning opportunity! Should I just move it and connect the heater center tap directly to ground instead?

When I get home from work I'll double check the grounds on the filter caps and make sure they are grounded. Now that the amp is running I plan to keep at it until I figure it out. If I can't make any progress I'll post some pics over the weekend.

Thanks so much for your help! I apologize again for not speaking clearly.

Ed

[surfsup]

What grounding scheme did you use?
Ed

I used my own. I have a gut shot here:

http://ampgarage.com/forum/viewtopic.ph ... 250#184250

The input and V1's cathodes/grounds including the mosfet are at the input jack. The others are grounded to their caps and run to a common chassis point. The first cap I ran separately, as well. YOu can see the wires zip tied together running to near the PT. My hum is nearly non-existent. I don't think you can totally remove hum on a SE can you? I'm about that close though. Good luck.

BTW, my extra cap is for my extra preamp tube, not extra resevoir filtering (though maybe I'll clip a cap in there and see).

[blues junkie]

I have an Eagle Supre that should be here on Wednesday . This will be my first build, so I'm very excited and a little nervous I've been doing alot of reading and research... so hopefully I don't screw up to bad.

Any advice from all you seasoned builders would be greatly appreciated.

Also a big thanks to RJ for being patient and answering all my questions.

[dorrisant]

Read... Read... and then, read some more....

There are plenty of people here more than willing to help...

Relax... And have a homebrew!

Tony

[surfsup]

blues, if you're like me and for the first build didn't have a variax, a bulb limiter, or anything...

I built it, then double checked all the connections vs the schemo, then came back the next day and triple checked it. Although I didn't mark it with a pen I found an easy way was to simple count how many leads met at a point on the schemo and count how many leads attached together in the amp. Very quick and will tell you immediately if something is wrong.

Then I reflowed ALL the joints, pulled out the DMM (I hope you have one) and measured continuity between the chassis and all the leads that attached to the turret/eyelet between the lead and chassis. Clip the black on the chassis, and put the red on the lead. This checks the solder joint to the turret and the solder joint from turret to the wire leading to the chassis, and the connection to the chassis so your ground(s) are good to go.

Then I checked all the other solder joints testing opposing leads to a turret/eyelet.

That made me far more comfortable flipping the power, then standby, though I was still freaking.

[Zippy]

Then I reflowed ALL the joints, pulled out the DMM (I hope you have one) and measured continuity between the chassis and all the leads that attached to the turret/eyelet between the lead and chassis.

FWIW, I find that being fastidious when making a solder joint obviates reflowing all the joints - better to do it right, do it well, the first time.

"Continuity" checks are in the right direction but not adequate. Some meters will beep their satisfaction but that's not what you want. Leads going to ground should read less than one ohm for a good ground. If they don't, find out why and fix it, else you'll start accumulating voltages and building ground loops.

Enjoy!

[surfsup]

I try to do it right the first time. Reflowing doesnt hurt though. Thanks for the tip on resistance checking my connections. I will use that from now on.